基于流固耦合理论的男性下尿路生物力学研究

发布时间：2018-11-07 15:12

【摘要】：男性膀胱下尿路梗阻发病率极高,任何年龄均可发生。下尿路梗阻早期的客观表现为尿动力学改变,故尿动力学检查可较早发现下尿路梗阻,但现有尿动力学检查手段对尿路正常生理活动存在干扰,并影响受检查者的精神和心理。针对上述问题,本文基于流固耦合理论对男性下尿路开展生物力学研究,为应用尿路流体仿真进行无创性尿动力学检测提供理论支撑,也为下尿路梗阻的诊断、治疗提供理论基础。本文首先应用火棉胶薄型化连续断层切片技术,阐明膀胱出口及尿道复杂结构,建立高度仿真的无梗阻、轻度梗阻、中度梗阻、重度梗阻四种下尿路几何模型(包括膀胱、前列腺、尿道膜部括约肌、尿道、尿液流场模型)。随后进行了两类、四组共23次仿真计算:在正常排尿过程逼尿肌压力范围内取5个压力值30、40、50、60、70cmH2O,分别对这5种逼尿肌压力下正常排尿过程进行流固耦合计算;在前列腺尿道梗阻排尿过程逼尿肌压力范围内取6个压力值50、70、90、110、130、150cmH2O,分别对这6种逼尿肌压力下三种不同程度前列腺尿道梗阻排尿过程进行流固耦合计算。经过数值模拟得到尿流率、排尿时压力-尿流率曲线、尿道压力分布等尿动力学参数及下尿路各器官的应力、变形情况。对正常排尿过程固体域VonMises应力、位移进行分析,结果表明膀胱颈、尿道膜部区域容易发生病变;正常排尿过程流体域分析结果表明流体域的总压、速度、涡量、壁面切应力随着入口压力升高,整体上逐渐变大,尿道后壁面承受的壁面切应力较大,较前壁面容易发生损伤。对前列腺尿道梗阻排尿过程固体域Von Mises应力、位移进行分析,结果表明梗阻情况较无梗阻情况膀胱颈区域更容易发生病变,且梗阻程度越严重,膀胱颈区域发生病变可能性越大;前列腺尿道梗阻排尿过程流体域分析结果表明梗阻情况下前列腺区域,特别是前列腺区域末端接近尿道膜部的位置容易发生病变,且梗阻越严重,前列腺区域末端接近尿道膜部位置越容易发生病变,整个尿道后壁面更容易发生病变,流体域各个部位的速度、涡量分布与梗阻程度不存在明显的联系。根据仿真结果绘制的压力-流率曲线以及尿道压力分布曲线,与临床检测结果一致,说明尿路流体仿真应用于尿道梗阻等下尿路疾病的诊断可行性较高,对于推动尿路流体仿真替代现有尿动力学检测手段具有重要意义。本文通过分析多种情况下的尿流动力学行为及其对下尿路的影响,为下尿路疾病的发展预判提供了参考,对其临床诊断、改进手术治疗方案起到了一定的指导作用。
[Abstract]:The incidence of subbladder obstruction in men is extremely high and can occur at any age. The early objective manifestation of lower urinary tract obstruction is the change of urodynamics, so urodynamic examination can find the lower urinary tract obstruction earlier, but the existing methods of urodynamic examination interfere with the normal physiological activities of urinary tract and affect the mental and psychological status of the subjects. In view of the above problems, the biomechanical study of male lower urinary tract was carried out based on fluid-solid coupling theory, which provided theoretical support for non-invasive urodynamic test using fluid simulation of urinary tract, and was also used for the diagnosis of lower urinary tract obstruction. Treatment provides a theoretical basis. In this paper, the technique of thin continuous slice section of sponge gum was used to clarify the complex structure of bladder outlet and urethra, and four kinds of geometric models of lower urinary tract (including bladder, bladder) were established, which were highly simulated without obstruction, mild obstruction, moderate obstruction and severe obstruction. Prostate, urethral sphincter, urethra, urine flow field model. Then two kinds of simulations were carried out in four groups. In the range of detrusor pressure during normal urination, 5 pressure values of 30 ~ 40 ~ 50U ~ (60) C ~ (70) cm _ H _ 2O were taken to calculate the fluid-solid coupling of the normal urination process under these five kinds of detrusor pressure. In the range of detrusor pressure of prostatic urethral obstruction (BUO), six pressure values of 50 ~ 70,90110130150cmH _ 2O were collected and calculated by fluid-solid coupling for three different degrees of prostatic urethral obstruction under these six kinds of detrusor pressures. The urodynamic parameters, such as uroflow rate, pressure-uroflow rate curve, urethral pressure distribution, and stress and deformation of various organs in the lower urinary tract were obtained by numerical simulation. The VonMises stress and displacement in the solid region during normal urination were analyzed. The results showed that the bladder neck and urethral membrane region were prone to pathological changes. The results of fluid domain analysis during normal urination showed that the total pressure, velocity, vorticity and wall shear stress of the fluid region increased with the increase of inlet pressure, and gradually increased as a whole. The wall shear stress on the posterior wall of urethra was larger than that on the front wall, which was more easily damaged than that of the front wall. The stress and displacement of Von Mises in the solid region during the urination process of prostatic urethral obstruction were analyzed. The results showed that the obstruction was more likely to occur in the bladder neck area than that in the non-obstruction condition, and the more serious the obstruction was, the more severe the urethral obstruction was. The greater the possibility of bladder neck lesion; The fluid domain analysis of urethral obstruction showed that the location of the prostate region, especially the end of the prostate region near the urethral membrane, was easy to occur in the case of obstruction, and the more serious the obstruction, the more serious the urethral obstruction was. The closer the end of the prostate region is to the urethral membrane, the easier it is to change the whole posterior urethral wall. There is no obvious relationship between the velocity and vorticity distribution of the fluid region and the degree of obstruction. The curves of pressure-flow rate and urethral pressure distribution were drawn according to the simulation results, which were consistent with the clinical results, which indicated that the application of fluid simulation in the diagnosis of lower urinary tract diseases such as urethral obstruction was more feasible. It is of great significance to promote urologic fluid simulation to replace existing urodynamic testing methods. By analyzing the urodynamic behavior and its influence on the lower urinary tract under various conditions, this article provides a reference for the development of lower urinary tract disease, and plays a certain guiding role in clinical diagnosis and improvement of surgical treatment.
【学位授予单位】：天津科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R318.01;R691.2

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